Help to fix some warnings

Hello, I have 4 warnings errors, can you help me please ? There is my DSDT.DSL

Intel ACPI Component Architecture
ASL Optimizing Compiler version 20091214 [Dec 16 2009]
Copyright (C) 2000 - 2009 Intel Corporation
Supports ACPI Specification Revision 4.0


/Users/Hazielou/Library/Application Support/EvOSoftware/DSDT/DSDTFiles/dsdt.dsl  3448:                             If (Or (ATKN (0x52), \AMW0.AMWN (0x6E)))
Warning  1093 -                                                                   Called method may not always return a value ^ 

/Users/Hazielou/Library/Application Support/EvOSoftware/DSDT/DSDTFiles/dsdt.dsl  6829:                             Return (DEVS (Arg2))
Warning  1093 -                                                                   Called method may not always return a value ^ 

/Users/Hazielou/Library/Application Support/EvOSoftware/DSDT/DSDTFiles/dsdt.dsl  6904:         Method (AMWN, 1, Serialized)
Warning  1088 -                                                      Not all control paths return a value ^  (AMWN)

/Users/Hazielou/Library/Application Support/EvOSoftware/DSDT/DSDTFiles/dsdt.dsl  7248:         Method (DEVS, 1, Serialized)
Warning  1088 -                                                      Not all control paths return a value ^  (DEVS)

ASL Input:  /Users/Hazielou/Library/Application Support/EvOSoftware/DSDT/DSDTFiles/dsdt.dsl - 8495 lines, 298462 bytes, 3719 keywords
AML Output: /Users/Hazielou/Library/Application Support/EvOSoftware/DSDT/DSDTFiles/./dsdt.aml - 31396 bytes, 903 named objects, 2816 executable opcodes

Compilation complete. 0 Errors, 4 Warnings, 0 Remarks, 32 Optimizations